The subject invention relates to a catheter assembly and, more specifically, to a direct central nervous system catheter assembly suitable for use for: the simultaneous measurement of intracranial pressure, draining of cerebrospinal fluid (CSF), delivery of therapeutic agents and/or drug(s) directly into the cerebrospinal fluid, and a temperature control system which can be coupled to the direct central nervous system catheter to prevent or reduce damage to the central nervous system.
By way of background, ventriculostomy catheters are commonly used to facilitate the drainage of cerebrospinal fluid (CSF) to reduce intracerebral pressure and can also be connected to pressure transducers for the monitoring of intracranial pressure (ICP). The increased use of ventriculostomy catheters can be directly associated with the publication of Guidelines to the Management of Severe Head Injury (Bullock et al. (1995) Guidelines for the Management of Severe Head Injury. San Francisco: Brain Trauma Foundation, Inc.; Rosner et al. (1992) J. Neurosurgery 76:399A; Rosner et al. (1990) J. Trauma 30:933-41; Rosner (1987) xe2x80x9cCerebral perfusion pressure: The link between intracranial pressure and systemic circulationxe2x80x9d. In Wood (ed.): Cerebral Flood Flow: Physiologic and Clinical Aspects. McGraw Hill, New York, N.Y., pp. 425-88, 1987). These Guidelines recommend the use of either a pressure bolt against the cerebral membranes or that a ventriculostomy be performed to directly measure ICP in all patients with a head injury and a Glascow coma score (GCS) of less than 10. Additionally, ventriculostomies are often utilized because of the added feature of allowing direct access to the CSF at the level of the brain. This is of particular importance as these catheters allow direct access to the CSF, which allows for direct withdrawal of CSF to control increased intracranial pressure, monitor drug levels or metabolites in the CSF (Kossman et al. (1996) J. Antimicrob. Chemother. 37(1):161-7), or to remove toxic substances from the CSF flow (Kristofet al. (1998) J. Neurol. Neurosurg. Psychiatry. 64(3):379-81).
Current ventriculostomy catheters are generally xe2x80x9copen systemsxe2x80x9d of the single lumen-type, and as stated above, are typically linked to pressure transducers to give measurements of ICP, and are used to facilitate the drainage of CSF to reduce intracerebral pressure by disconnecting the pressure monitor and extracting. CSF fluid, and then reconnecting the pressure monitor. This creates the potential for the introduction of infectious agents which can cause infections such as ventriculitis or meningitis. As such, one of the most significant concerns of intracranial pressure monitoring is the potential introduction of pathogens into the CNS resulting in ventriculitis, meningitis and cerebral abscesses (Rossi et al. (1998) Acta Neurochir. Suppl. 71:91-3; Khan et al. (1998) Acta Neurochir. Suppl. 71:50-2; Guyot et al. (1998) Acta Neurochir. Suppl. 71:47-9; Holloway et al. (1996) J. Neurosurg. 85(3):419-24). The current ventriculostomy catheters are not designed, nor was it ever envisioned, that they would be used for drug delivery directly into the CSF. Furthermore, they are not generally approved for this use although some instances have been reported where they have been used for the delivery of antibiotics into the CSF. However, use of current ventriculostomy catheters in this manner remains a xe2x80x9cnon-approved use.xe2x80x9d
Similar to the present day ventriculostomy catheters, spinal catheters having an external port have been utilized for many years for the sampling of CSF and for the delivery of medications to the CSF in and around the spinal cord. These medications include anesthetics and acute pain medications. In animal models of induced CNS injury it has been suggested that intrathecal or intraventricular delivery may be of use to attenuate the amount of injury (Buki et al. (1999) J. Neurotrauma 16(6):511-21).
While the current ventriculostomy catheters and spinal catheters have been utilized for the introduction of drugs or medications therethrough, the current types of these catheters are not specifically designed for the delivery of drugs therethrough and, hence, impart drawbacks, the most critical of which includes the opportunity for and the introduction of infectious agents directly into the cerebral spinal fluid causing, for example, ventriculitis and/or meningitis.
It is known that in order to prevent or reduce injury or damage to elements of the central nervous system, such as the brain or spinal cord, that artificial conditions can be induced in the central nervous system such as the induction of a coma to slow the metabolism of the brain to keep its tissues viable. One such method for accomplishing this end is disclosed in U.S. Pat. No. 5,149,321 to Klatz et al. in which chilled drug containing fluids are delivered to the brain through catheters inserted in blood vessels such as the carotid artery. However, the prior art does not teach a method for directly maintaining or controlling the temperature of the CSF to aid in the treatment of central nervous system injuries.
Temperature has been linked to the degree of injury in CNS trauma induced in animals (Clark et al. (1996) J. Cereb. Blood Flow Metab. 16(2):253-61; Whalen et al. (1997) J. Neurotrauma 14(8):561-72). In essence, if the temperature can be lowered there will be a reduction in the area and amount of neuronal damage (Dietrich (1992) J. Neurotrauma 9 Suppl. 2:S475-85; Dietrich et al. (1996) Adv. Neurol. 71:177-94, discussion 194-7; Palmer et al. (1993) J. Neurotrauma 10(4):363-72). It has recently been theorized that a local reduction in the area of injury is required to reduce the amount and extent of induced injury to the brain while avoiding the complications associated with whole body cooling (Dietrich et al. (1996) Adv. Neurol. 71:177-94, discussion 194-7). It is likely that these same principles apply to spinal cord injury.
Accordingly, it would be both advantageous and desirable to have a catheter design which allows both direct access to the central nervous system (CNS) (e.g., the cerebral spinal fluid disposed about the brain and/or spinal cord) which would facilitate the measurement of ICP, the removal of CSF under aseptic circumstances, the aseptic introduction of therapeutic agents and/or drugs directly into the cerebral spinal fluid, and which can be combined with a temperature control system to control the temperature of the CSF to prevent or reduce damage to the central nervous system and to facilitate treatment of an individual in need of such treatment.
In accordance with the present invention, there is provided a direct central nervous system catheter which can be directly inserted into the ventricle space or spinal canal to provide access which enables the sampling of the CSF and/or monitoring of intracranial pressure while at the same time facilitating the aseptic delivery of therapeutic agents and/or drugs directly into the cerebrospinal fluid and the management of CSF temperature. The direct CNS catheter includes a catheter body defining at least one lumen and having a drug delivery branch, a monitoring/sensing branch, and optional branches if desired each branch being connected in fluid communication with the lumen. Both the drug delivery branch and the monitoring branch have at least one proximally disposed opening which provides for the introduction and/or removal of fluid therefrom. The drug delivery branch of the catheter assembly includes a filter connected in fluid communication therewith to remove any pathogens from a therapeutic agent and/or drug(s) delivered to the cerebrospinal fluid through the branch. The catheter assembly can also include a one-way valve for the introduction of drugs, fluids or medications through the catheter assembly with no back-flow of the introduced materials. With this design, the catheter assembly limits the introduction of pathogens into the system and reduces the potential contact of the health care provider to bodily fluids. Finally, the catheter assembly reduces the risk of losing an introduced therapeutic agent due to back-flow. The drug delivery branch is disposed distally to a sampling branch which allows for the withdrawal of fluids. The monitoring branch allows for direct measurement of CSF pressure using monitoring or sensing equipment. This includes monitoring pressure waves of the cerebrospinal fluid through the end of the catheter placed in the ventricle or spinal canal of a brain. The catheter assembly can also include a control valve disposed in fluid communication with an optional branch which includes an in-line one-way valve that allows the direct sampling of the cerebrospinal fluid for either laboratory testing or to lower intracranial pressure in a sterile fashion. The monitoring branch is connected in fluid communication with the catheter body through a second control valve. The monitoring branch allows for pressure monitoring or sensing and the control valve allows for the measurement of intracranial pressure in a first position wherein an open fluid pathway is established between the portion of the catheter disposed in the ventricle or spinal canal and the monitoring branch and wherein fluid communication between the portion of the catheter in the ventricle or spinal canal and the fluid sampling branch is closed. The control valve is movable to a second position wherein fluid communication between the portion of the catheter inserted in the ventricle or spinal canal and the sampling branch is opened whereby fluid can be extracted from the patient. In the second portion, fluid communication between the pressure monitoring branch and the portion of the catheter disposed in the ventricle or spinal canal is closed.
The catheter assembly provides a xe2x80x9cclosed systemxe2x80x9d which means that the system is not open to the atmosphere. Once the catheter is constructed from its modular connections, there is no reason to open the closed system for either drug delivery, pressure monitoring, temperature management, or CSF sampling and withdrawal.
Also in accordance with the present invention, there is provided a temperature control system for use in controlling the temperature of a location within the central nervous system such as the brain or the spinal cord. The temperature control system includes a temperature control mechanism including a pump operatively connected in fluid communication to a heat exchanger. The heat exchanger includes a closed-loop conduit system connected in fluid communication with the heat exchanger which can be placed within and/or adjacent to a portion of the central nervous system of a patient through, for example, insertion in an optional branch of the direct central nervous system catheter which has been placed in contact with a portion of a subject""s central nervous system. The system further includes a pump controller, a central processing unit or controller, and a power supply all operatively connected to the temperature control mechanism.